Treatment of dry eye: an analysis of the British Sjögren's syndrome association comparing substitute tear viscosity and subjective efficacy.

PURPOSE: This study aims to address the lack of independent subjective efficacy data on artificial tear substitutes in the treatment of dry eye due to the anecdotal association of 'thicker' products being more effective. METHODS: This is an independent study of the subjective use and efficacy of topical treatments used by members of the British Sjögren's Syndrome Association (BSSA) related to product viscosity. 2000 members of the BSSA were sent a questionnaire regarding their physical condition and the use of artificial tear substitutes. Viscosity analysis was performed on the most popular preparations. Statistical comparison is made between subjective efficacies related to substitute tear viscosity. RESULTS: 1088 patients responded giving information regarding their condition together with the subjective use and efficacy data of artificial tear substitutes. Visco-analysis was performed on the most popular preparations; these had more than 50 patients using them. In terms of subjective benefits related to viscosity for 'frequency' and 'duration' the data suggests a general trend toward viscous preparations being instilled less frequently and lasting longer; however this was not shown to be significantly correlated and some interesting comparisons are reported. CONCLUSIONS: The results confirm high levels of ocular lubricant use in the BSSA population. Our data investigates the often-anecdotal evidence that thicker preparations are more effective. However, we did not find this correlation to be statistically significant suggesting further study into factors related to subjective product efficacy. These results lay foundations for the development of future products in the treatment of severe dry eye.

Modified Ruiz procedure for reducing high astigmatism after penetrating keratoplasty.

PURPOSE: To evaluate the refractive, keratometric, and visual outcomes of a modified Ruiz procedure in patients with high astigmatism after penetrating keratoplasty (PKP). METHODS: Retrospective cohort study with 26 eyes of 24 patients. A modified Ruiz incision pattern was used. Two paired arcuate incisions, centered on the preoperative cylinder axis, were performed over 2 o'clock hours (60 degrees) within the graft. The median optical zone was 4.5 mm (range, 3-5 mm). Subsequently, 4 radial cuts were made. The depth of all cuts was 90%-95% of the central corneal thickness. The follow-up time was 3 months. RESULTS: The mean preoperative subjective cylinder was 8.75 +/- 3.05 D, decreasing to 5.31 +/- 3.12 D postoperatively. Three months after the procedure, 53.8% of the eyes had <5.0 D of refractive astigmatism and 47% of eyes had <5.0 D of keratometric astigmatism. For the refractive data, the mean correction index was 1.95; the mean index of success was 1.27. The mean reduction in spherical equivalent was 1.95 D (60.5%). The mean best-corrected visual acuity (BCVA) was 0.61 and did not change significantly. Three eyes gained 2 or more lines of BCVA, and 1 eye lost 2 or more lines of BCVA. There was no difference in subgroup analysis of eyes treated with 4- (13 eyes) or 5-mm (12 eyes) optical zones. CONCLUSIONS: The modified Ruiz procedure is an effective method to reduce high astigmatism after PKP. However, the results were widely scattered, and the patients need to be informed about the unpredictable outcome and its consequences.

A normative zone of RPE ratings for use during graded exercise testing.

The purposes of this investigation were to identify a zone of normality for ratings of perceived exertion (RPE) and to compare the RPE responses in patients with coronary artery disease to this zone. The zone was generated from RPE estimated during the last minute of each stage of a Bruce treadmill test in 44 normal adult men. RPE were regressed against the corresponding MET level for each exercise stage. The zone was established as the 95% confidence interval (CI) spanning the average RPE vs MET regression line. RPE estimated during the last 1.0 min. of a Bruce or Modified Balke treadmill test administered to adult men (n=37) with coronary artery disease were compared to the 95% CI zone. A total of 19 (51%) of the coronary artery disease patients estimated RPE during a progressively incremented treadmill test that were above the zone, indicating a comparatively greater than normal perception of strain for a given metabolic stress. The presently generated zone provides a practical use of RPE in the interpretation of clinical exercise tests.

Deep Anterior Lamellar Keratoplasty (DALK): visual outcome and complications for a heterogeneous group of corneal pathologies.

PURPOSE: To review the visual outcome and complications of deep anterior lamellar keratoplasty (DALK), using Melles technique. METHODS: All patients undergoing DALK between December 1999 and March 2005 were routinely entered into a longitudinal study. DALK was attempted in 80 eyes of 68 consecutive patients. Descemet membrane perforation occurred in 11 eyes, of which 7 required conversion to penetrating keratoplasty. The visual and refractive outcome of these eyes is presented separately. The mean follow-up was 21.2 months. Best-corrected visual acuities (BCVAs), refraction, graft clarity, and complications were recorded at each visit and analyzed. RESULTS: The mean patient age was 34.2 years. Keratoconus was the main indication for surgery (58 eyes), followed by herpes simplex keratitis (6 eyes), corneal stromal dystrophy (5 eyes), stem cell failure with scarring (2 eyes), corneal dermoid (1 eye), and corneal opacity (1 eye). The mean central corneal thickness changed from 0.42 +/- 0.07 mm preoperatively to 0.62 +/- 0.06 mm postoperatively. At latest follow-up, BCVA of 6/6 or better was present in 24.7%, 6/9 or better in 69.9%, and 6/12 or better in 84.9% of the eyes. The mean postoperative refractive cylinder was 3.31 +/- 2.59 D, and the mean spherical equivalent was -2.54 +/- 3.61 D; 52.2% of the eyes had a refractive cylinder less than +/-3 D and 49.3% of the eyes had a spherical equivalent less than +/-3 D. Rejection episodes occurred in 9.6% of the eyes but were successfully reversed in all eyes. Graft failure occurred in 1 eye with severe stem cell deficiency. CONCLUSION: This is the largest series of DALK cases using the Melles technique in a variety of corneal lesions. Our results confirm the usefulness and safety of this procedure in conditions with no endothelial involvement. Graft rejection remains a significant complication but is associated with good recovery because the endothelium is spared.

Capabilities of potential vision test measurements: clinical evaluation in the presence of cataract or macular disease.

PURPOSE: To determine the usefulness of a battery of potential vision tests (PVTs) including potential acuity meter (PAM), laser interferometer (LI), critical flicker/fusion frequency (CFF), superilluminated pinhole at distance (SPH(d)) and near (SPH(n)), and optimal reading speed (ORS) by their independence of the effects of cataracts and sensitivity to macular disease (MD). SETTING: Department of Optometry, University of Bradford, Bradford and Leeds General Infirmary, Leeds, United Kingdom. METHODS: Potential vision test measurements were determined in 76 patients with age-related cataract and no other eye disease, 52 patients with MD and clear ocular media, and 28 patients with normal, healthy eyes. RESULTS: Potential vision tests were independent of the degrading effects of cataract up to a visual acuity (VA) level of 20/200 or worse (CFF), 20/125 (ORS and SPH), and 20/40 (PAM and LI). A high degree of association was found between PVT scores and distance VA in the MD group for SPH(d) (r2 = 0.93), SPH(n) (r2 = 0.89), and PAM (r2 = 0.71). A moderate correlation was found for LI (r2 = 0.55), CFF (r2 = 0.50), and ORS (r2 = 0.45). CONCLUSIONS: Potential acuity meter and LI showed very limited independence to moderate/dense cataracts and inaccurate predictions in patients with MD. Superilluminated pinhole was relatively unaffected by moderate/dense cataract and yet provided accurate predictions in the presence of MD and clear ocular media. Critical flicker/fusion frequency showed the greatest ability to bypass cataracts, although its ability to predict VA in patients with early MD was limited. The ORS was relatively unaffected by moderate/dense cataract, but its poor ability to predict VA in MD may limit its clinical suitability as a PVT.

Improving subjective scaling of pain using Rasch analysis.

UNLABELLED: Pain management outcomes assessment depends on valid measurement of pain. However, the validity of single-item scales, such as numeric or faces scales, with the assignment of ordinal numerical values to response scale categories, is questionable. The universal assumption that equal distances between response choices represent equal distances on the dimension being measured is essentially erroneous. Herein we demonstrate that Rasch analysis can be used to expose and repair scale inequity and reengineer scale structure. Thirty-one subjects with severe ocular surface disease repeatedly completed a 7-category faces pain scale. Rasch analysis demonstrated that response category 5 was underutilized, leading to disordering of the response scale. Collapsing category 5 into either category 4 or 6 produced an ordered 6-category faces scale that could be recalibrated with average Rasch person measures to create linear measurement on a continuous latent variable. The value of further alterations to the scale was explored, and the implication for scale redesign discussed. Rasch analysis could be applied to any subjective pain measure post-hoc to create linear measurement or applied during instrument development to optimize design. PERSPECTIVE: Single-item scales like the faces scale or a 1-10 numerical rating scale are commonly used for the subjective assessment of pain. However, scores applied to response categories are arbitrary, so do not represent equidistant steps in the underlying latent variable (pain). Scale inequities are easily demonstrable and repairable with Rasch analysis.

Effect of cataract surgery incision location and intraocular lens type on ocular aberrations.

PURPOSE: To determine whether Hartmann-Shack wavefront sensing detects differences in optical performance in vivo between poly(methyl methacrylate) (PMMA) and foldable acrylic intraocular lenses (IOLs) and between clear corneal and scleral tunnel incisions and whether optical differences are manifested as differences in visual performance. SETTING: Department of Optometry, University of Bradford, West Yorkshire, United Kingdom. METHODS: This study comprised 74 subjects; 17 were phakic with no ocular pathology, 20 had implantation of a Pharmacia 722C PMMA IOL through a scleral tunnel, 21 had implantation of an Alcon AcrySof IOL through a scleral tunnel, and 16 had implantation of an AcrySof IOL through a corneal incision. Visual acuity and contrast sensitivity testing, ocular optical quality measurement using Hartmann-Shack wavefront sensing, and corneal surface measurement with a videokeratoscope were performed in all cases. RESULTS: There were significant differences between groups in the total root-mean-square (RMS) wavefront aberration over a 6.0 mm pupil (F=3.91; degrees of freedom=3,70; P<.05) mediated at the 4th-order RMS, specifically spherical and tetrafoil aberrations. The PMMA-scleral group had the least aberrations and the AcrySof-corneal group the most. For a 3.5 mm diameter pupil, the total higher-order RMS wavefront aberration was not significantly different between the groups (P>.05). There were no differences between groups in corneal shape, visual acuity, or contrast sensitivity. CONCLUSIONS: Implantation of the spherical PMMA IOL led to a slight reduction in total wavefront aberration compared to phakic eyes. AcrySof IOLs induced more aberrations, especially spherical aberration. Corneal-based incisions for IOL implantation compounded this increase. Studies of the optical performance of IOLs in vivo should use wavefront sensing as the main outcome measure rather than visual measures, which are readily confounded by multiple factors.

Development of a critical flicker/fusion frequency test for potential vision testing in media opacities.

PURPOSE: To determine whether critical flicker/fusion (CFF) thresholds fulfill the criteria for a potential vision test (PVT) by being unaffected by media opacity yet affected by retinal disease. METHODS: CFF thresholds for three different stimulus sizes (0.5, 1.0, and 1.5 degrees ) were measured in 72 patients (mean age, 78.43 +/- 7.07 years) comprising 31 subjects with media opacity, 21 with macular disease, and 20 with pseudophakia. RESULTS: There were no statistically significant differences between CFF values from the media opacity and the pseudophakia groups for any target size (p > 0.10). However, CFF values were significantly lower in patients with macular disease for all the target sizes (p < 0.05). Analysis of a subset of six subjects with media opacity and seven subjects with macular disease and visual acuity of 20/200 or worse showed the media opacity group still had similar CFF values as the pseudophakia group and had significantly higher CFF than the macular disease group. CONCLUSIONS: CFF testing is shown to fulfill the requirements for a PVT and may prove to be particularly useful for patients with dense media opacity.

Sequestered viscoelastic after deep lamellar keratoplasty using viscodissection.

PURPOSE: Deep lamellar keratoplasty (DLKP) is an intricate procedure that preserves the host's endothelium, thus eliminating the possibility of endothelial graft rejection and potentially offering great benefits over penetrating keratoplasty. DLKP may be performed by a variety of techniques including viscodelamination, in which the stroma is separated from Descemet's membrane using viscoelastic. METHODS: Here we present an operative complication of this technique, which was not initially recognized, that caused significant morbidity to our patient and eventually led to the eye requiring a full thickness regraft. We also attempt to reproduce the lesion using nonviable cadaver corneas and illustrate histologically the nature of the corneal stroma and its relationship to Descemet's membrane following viscoelastic delamination.